Hummingbirds are the only family of birds that can truly hover in still air for any length of time. They need to do so in order to hang in front of a flower while they perform the delicate task of inserting their slim, sharp bills into its depths to drink nectar. Their thin wings are not contoured into the shape of aerofoils and do not generate lift in this way. Their paddle-shaped wings are, in effect, hands that swivel at the shoulder. They beat them in such a way that the tip of each wing follows the line of a figure eight lying on its side. The wing moves forward and downwards into the front loop of the eight, creating lift. As it begins to come up and go back, the wing twists through 180 degrees so that once again it creates a downward thrust. The hummingbird's method of flying does have one major limitation: the smaller a wing, the faster it has to beat in order to produce sufficient downward thrust. An average-sized hummingbird beats its wings 25 times per second. The bee hummingbird, native to Cuba, is only two inches (five centimeters) long and beats its wings at an astonishing 200 times per second.